High-impact portable riveting apparatus

ABSTRACT

A HIGH-IMPACT TOOL IS DISCLOSED AS PART OF A RAM COMPONENT OF AN ELECTRO-MECHANICAL GUN, AS SHOWN IN FIG. 1, WHICH CONVERTS A RAPIDLY CHANGING ELECTRIC CURRENT PASSING THROUGH ITS COIL INTO A MECHANICAL FORCE ACTING BETWEEN A CONDUCTOR PLATE ON THE RAM AND THE COIL TO PROPEL THE RAM AND ITS FORMING SURFACE AGAINST A WORKPIECE TO FORM IT. A PAIR OF PORTABLE ELECTRO-MECHANICAL RIVERTING FUNS, AS SHOWN IN FIGS. 3-7, IS DESCRIBED ALONG WITH AN ELECTRICAL SYSTEM, SHOWN IN FIG. 8, WHICH INTERLOCKS THEIR OPERATION TO INSURE A SIMULTANEOUS RAM IMPACT ON EACH END OF THE RIVET. THE POWER SUPPLY, FOR OPERATOR SAFETY, IS ISOLATED FROM GROUND AS IT DISCHARGES THROUGH THE COILS. A SYSTEM, SHOWN IN FIGS. 5-7, FOR PROPER GUN ALIGNMENT IS DISCLOSED WHEREIN INCREASED BACK-PRESSURE OF FLUID OR GAS OUTLETS, BLOCKED BY PROPER GUN POSITIONING AGAINST THE WORKPIECE, OPERATES CONTROL SWITCHES PERMITTING FIRING OF THE GUNS.

Feb. 2, 1971 H. A. SCHMITT ET AL HIGH-IMPACT PORTABLE RIVETING APPARATUS Filed Nov. L5, 1968 'I5 Sheets-Sheet 1 `nc Power souRcE ,4

"In Dc POWER 5d 3M .SOURCE Fm/D 220 gmk sa/0M Feb. 2, `1971 H, A, sCHMrr-r AET AL 3,559,269

HIGH-IMPACT PORTABLE RIVETING APPARATUS Filed Nov. L5, 1968 5 Sheets-Sheet 2 Feb. 2, 1971 H. A. SCHMITT ETAL HIGH-IMPACT PORTABLE IVETING APPARATUS Filed Nov. L5, 1968 3 Sheets-Sheet 5 Aw/ A25/mv @muy /A/ 302 ,4L/Mm AUX /69 Jig/30% READY l /79 303 cf/W65 3%? @L E *i* l l l /Z @Weka/PMB l 570/9 /w//v CHA/65D h mms/70H5.- A/f A 5MM/77 M60/5H s. SEA/#0N SAM WW United States Patent O U.S. Cl. 29-243.54 16 Claims ABSTRACT F THE DISCLOSURE A high-impact tool is disclosed as part of a ram component of an electro-mechanical gun, as shown in FIG. 1, which converts a rapidly changing electric current passing through its coil into a mechanical force acting between a conductor plate on the ram and the coil to propel the ram and its forming surface against a workpiece to form it. A pair of portable electro-mechanical riveting guns, as shown in FIGS. 3-7, is described along with an electrical system, shown in FIG. 8, which interlock-s their operation to insure a simultaneous ram impact on each end of the rivet. The power supply, for operator safety, is isolated from ground as it discharges through the coils. A system, shown in FIGS. 5n7, for proper gun alignment is disclosed wherein increased back-pressure of fluid or gas outlets, blocked by proper gun positioning against the workpiece, operates control switches permitting tiring of the guns.

BACKGROUND OF THE INVENTION This invention relates to apparatus for mechanically forming material and relates more particularly to a singleimpact portable riveting apparatus.

DESCRIPTION OF THE PRIOR ART In modern manufacturing operations there are many requirements for tools suitable for forming workpieces in a minimum time at a reasonable cost. Oftentimes the workpiece is quite large or already installed on a larger structure thereby establishing a requirement that the forming tool be portable so that it can be brought to the workpiece.

In the situation where metal parts or other high-strength materials need to be formed, the high energy requirement for the forming tool seems to dictate the need for a massive tool size. To produce high-quality structures it is important that the forming operations involved in fastening the structures together be of a high degree of uniformity.

In normal riveting processes wherein high-impact forces are required, these are generally applied by means of a repeated series of blows from the riveting tools against the rivet. Such rapid cycling of the impacting tool against the rivet puroduces a high noise level which becomes intolerable to those in the immediate vicinity after a short duration of exposure. Such noise fatigue reduces worker production and morale.

From the foregoing it is apparent that there is a need for a portable, high-impact tool which can be operated to produce a predictable and repeatable high-energy impact against workpieces with a minimum of noise.

In manufacturing operations involving the use of electrical tools wherein high currents and voltages are involved, shock hazards to the operators often prevent the wide use of such tools. Thus there is a need for means Patented Feb. 2 1971 ICC which will reduce the shock hazard for operators of equipment utilizing surges of high voltage electric current in their operation.

For froming processes involving high forces applied in opposite directions to the workpiece the misalignment of the tools applying the forces may cause damage to the workpiece because of undesired distortion thereof. In addition the workpiece may be flexed and bent if the impacts on opposite sides do not occur simultaneously. Thus there is a need for means which will insure the proper alignment and simultaneous operation of high impact tools.

OBJECTS AND SUMMARY OF THE INVENTION In view of the needs related above it is the principal object of the instant invention to provide a generally improved high-impact workpiece-forming apparatus.

It is another object of the instant invention to provide a high-impact apparatus having adequate components for producing workpiece-forming forces, but of a light enough construction to permit portability.

Yet another object of the instant invention is to provide in the electrical system for a high-impact tool a means for precisely controlling the impact force to yield repeatable predictable and highly uniform workpiece-forming operations.

A further object of the instant invention is to provide a generally improved single-impact riveting apparatus utilizing opposed rivet-driving tools and having an electrical system wherein the impacton one end of the rivet by one of the pair of guns is at substantially the identical instant that the other end of the rivet receives an impact from the other riveter.

A still further object of the instant invention is to provide in a portable high-impact tool a workpiece alignment sensing system which through suitable controls prevents the operation of the tool when it is improperly positioned relative to the workpiece.

It is another object of the instant invention to provide a control system which prevents an operating connection between an electrical energy source and a plurality of electrically operated tools until each of the selected set of said tools is in the proper operation alignment position and their respective operators are ready for the operation to take place.

A still further object of the instant invention is to provide a mans for isolating the electrical energy source for a high-impact tool during the operating cycle of its electrical components to thereby reduce the shock hazard for the tools operator.

In accordance with the present invention a workpiece-forming ram member is propelled against the workpiece through the interaction between an electrically conductive surface of the ram and an electrically conductive coil when the coil carries a rapidly changing electric current. The apparatus in addition provides a guiding structure for the ram such that its workpiece-forming surface will be guided in its movement as the ram moves. A recoil mass includes and reinforces the coil moving with it in an opposite direction to the movement of the ram. The recoil mass is resisted in its movement by a recoil absorbing system. A restoration spring may constitute the recoil absorbing system as well as a mechanism for repositioning the recoil mass to its initial position adjacent the ram, awaiting another surge of rapidlychanging current through the coil. In a riveting operation two such apparatus are positioned to oppose one another such that the ram of one riveter moves in the exact opposite direction to the ram of the opposed riveter. A series connection between the propelling coil in one through the propelling coils, lthe supply of electric energy foi the .current is isolatedfrom ground so that the operators body ydoes not become a part of the circuit due .to an insulation breakdown. 't

To provide p'roperalignment betweenV the path of the ram tand the `workpiece being riveted, a plurality of channels is formed in the working end of the portable riveting guns. The outlets of the channels are formed in the end of the gun positioned in contact with the workpiece in' .an array around the opening through which the rivet extends. Fluid or gas under pressure is supplied to th channels and exits from the outlets. The blocking of the outlets by theworkpiece or its support, wl1en the gun is properly aligned, increases the backpressure on the fluid to a preset value which is sensed by a pressure-sensitive switch in communication with the channels. As the back-pressure reaches the amount which indicates that all of the outlets are blocked and lthe gun and workpiece are in proper alignment, the pressure switch is cycled providing a signal to the controls that the gun is in proper alignment.

These and other features and advantages of the invention will become more clearly apparent from the following detailed description thereof, which is to be read with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. l is a diagrammatic view, with portions shown in cross section, of a generalized embodiment of a highimpact apparatus made in accordance rwith the instant invention;

FIG. 2 is a diagrammatic view similar to FIG. l but showing a simultaneously operated opposed pair of riveters made in accordance with the instant invention;

FIG. 3 is a side elevation view illustrating a riveting system utilizing an opposed pair of portable riveters made in accordance with the instant invention;

FIG. 4vis an isometric view, with some parts broken away for clarity, illustrating one of the portable riveters shown in FIG. 3;

PIG. 5 is a schematic view of theworking end'portion of the riveters shown in FIG. 3 illustrating the'structure and con-trol circuit for the alignment system made in accorda-nce with the instant invention;

FIG. 6 is an end elevation view, taken from lines 6-6 of FIG. 5, illustrating `the working end of one of the riveters;

FIG. 7 `is an enlarged sectional view of one outlet of the alignment system as seen from lines 7--7 of FIG. 6;

FIG. 8 is a schematic view illustrating the electrical system lfor the riveting system shown in` FIG. 3.

DESCRIPTION oF THE PREFERRED EivnsoDIr/IENTS To provide a general understanding of the working principle of the several embodiments of the instant invention, reference is directed initially `to the generalized embodiment of impact toolll illustrated schematically in FIG. 1. As shown, power supply 3 iswconnected to coil 10 which is structurally `supported by recoil system 20. In the ,initial position as shown in solid lines, ram 35 is positioned adjacent coil working face cover 13 so that the rams workpiece-forming member 40 is properly positioned for forming workpiece 45 supported through workpiece holder 47 by frame strong-back member 50.

Coil 10 may be formed of a continuous ribbon of conductive material such as at copper wire and pro- -tected by nonconductive cover ,13 positioned at its working end. Central terminal 11 of coil .10 `is connected to power supplyV 3 by discharge lead 8 and outer terminal 12 is .connectedto-power supply -3 by means of discharge lead 9.Power supply 3 also includes power source 4 which is connected through charging leads 6 and normally closed control switch4 7 to' variable capacitor 5, Once ,it is desired that the charge stored by capacitor 5 be Vpermitted to discharge through coil 10, control switch 7 is actuated toits dashed line position to connect dischargingnleads 8, .r9 to `both sides of,l capacitor 5. The quantity of electric' energy is controlled for reliable repeatability of the impacts by varying the voltage stored Iby variable capacitor 5. Although power supply 3 is described with reference to a control switch 7, it should be understood that normal switches and relays would not be used for high current switching and that thyratrons are represented herein by switches for simplicity.

Surrounding the recoil end of coil 10 is a reinforcing structure which, along with the weight of coil 10, is referred to generally as recoil mass 15. As shown, rod

member 17 projects in a first direction, as shown by the arrow 19, from coil 10 toward recoil absorption system 20. Fluid motor25 houses piston 26 which is fixed to rod 17 and slides along cylinder 2-'7 formed within fluid motor 25 to cause pressure fluid 28 to be compressed and forced around piston 26 as recoil mass 15 causes the rod 17 to move in the first direction 19 from the solid line position to the dashed line position. To restore recoil mass 15 including coil 10 to-its solid line position from the dashed line position, restoration spring 30 is positioned to sur round rod v17 and act between recoil mass 15 and fluid motor 25.

Ram is configured so that it includes a conductive surface, such-as conductor plate 37, having asize substantially equal to working face cover 13 of the coil 10 and is positioned initially adjacent to cover `13. As coil 10 is subjected to the discharge from capacitor 5, the rapidly changing electric current causes a repulsion between coil'10`and conductor plate 37 of ram 35, Vthereby propelling recoil'niass 1S vincluding coil 10 in first direction 19 while. ram 35 is propelledin a second direction, yshown by arrow 38', directly opposite to first direction 19. Ram

l 35 includes stem member 39 extending from conductive plate 37 in second direction 38 and terminating at workpiece-forming member 40, which is shown as being chiselshaped. Member 40 maybe joined to stem 39 by a detachable connection, such-that various sizes and shapes of workpiece-forming members 40 can be utilized. For simplicity workpiece hasbeen` shown as a simple stock member held in holder 47 `which extends upwardly from frame `strong-back 50. Also rigidly connected to strongback 50 is an upright structure forming ram guide.52 throughwh'ich the ram stem 39 extends. At the recoil end ofk apparatus 1'` there are positioned upright backstop members 54`secured at their lower ends to frame strongback' 50 and connected through suitable pin connectors 55 to fluid motor 25. i

Inoperiation, the initial condition for embodiment 1 is shown in solid lines. Capacitor 5 is charged by means of its rconnection through charging lead 6 to a suitable power source 4. Coil 10 is positioned adjacent to conductor plate '37`of ram'35. Workpiece 45 is held in a discharging leads 8 and 9 into coil 10 to produce a rapidly changing electrical current. A repulsion force between conductor plate 37 and coil 10 is developed of such a magnitude that ram 35 is propelled in second direction 38 with such force that workpiece 45 receives a tremendous impact from workpiece-forming member 40 positioned at the working end of ram stem 39. At the same time recoil mass is subjected to a recoil force opposite to that propelling ram 35, such that recoil mass 15, including coil 10, moves to the dotted line position shown. This movement compresses restoration spring 30 as well as pressure fluid 28 trapped between the piston 26 and cylinder walls 27 of fluid motor 25 until the recoil energy has been absorbed. At this time restoration spring 30 restores recoil mass 15 to its initial solid line position with the ram 35 reaching its initial position as it rebounds from impacting workpiece 45. If a higher impact force is required variable capacitor 5 is changed to increase the voltage on the capacitor. In a like manner, if a lesser impact is needed, a lesser voltage will be stored by variable capacitor 5. Once a desired impact force has been obtained, the system can be recycled with very good repeatable and consistent forming results being obtained.

It has been found that one manufacturing operation, namely riveting, can be performed utilizing the principle of operation wherein a rapidly changing electric current in an adjacent coil is utilized for propelling the conductive surface of a rivet forming ram to form the rivets in a single impact. Such an operation reduces the noise of multiple impact riveters to that of a single impact. In addition the exact control available for producing impact repeatability obtained through the use of an adjustable power supply, results in improved and more uniform structural fastening.

As an example of one suitable riveting system utilizing this principle, reference is directed to FIG. 2 wherein second embodiment high-impact system 60 is shown Power supply 63 is substantially identical to power supply 3 of the embodiment 1 shown in FIG. 1. It includes power source 614 which is capable of charging variable capacitor 65 through charging leads 66 when control switch 67 is in the solid line position. Power supply 63 is used to provide a rapidly changing electric current to both left and right-hand opposed riveters `68 and 69. Left-hand riveter 68 includes coil 70 which is connected to power supply 63 by means of discharge lead 72 connected to its center terminal 74. Right-hand riveter 69 includes coil 71 which is connected to power supply 63 by means of a discharge lead 73 attached to its center terminal 75. The outer terminal 76 of coil 70 is connected to outer terminal 77 of coil 71 by means of series connector 79.

Coil 70 of left-hand riveter 68 is protected by insulated working surface cover 82 and surrounded by recoil mass 86 which extends to a first direction, as shown by arrow 84, from working surface cover 82. A friction surface 88 on recoil mass 86 makes contact with support surface 90. A resisting force F is schematically shown by arrow 92 pushing recoil mass 86 in the second direction, as shown by arrow 85, directly opposite rst direction 84.

In a similar manner right-hand opposed riveter 69 protects its coil 71 by working surface cover 83 and recoil mass 87 which extends from the working surface 83 in second direction 85. Recoil mass 87 includes a friction surface 89 supported by support surface 90 and a right-hand resisting force F schematically illustrated by arrow 93, is shown pushing recoil mass 87 in rst direction 94. Immediately adjacent to working surface cover 82 of the left riveter 68 is positioned conductor plate 98 of ram 96. At the opposite end of ram 96 is positioned the workpiece-forming tool shown as rivet die 102 secured to the ram stem 104. The movement of ram 96 is guided by means of ram guide 108 through which passes ram stern 104. A rivet 111 is shown in the path of rivet die 102 as its is moved in second direction 85. Rivet 111, at

its other end, is in the path of rivet die 103 positioned at the end of ram stem 105 of righ-hand ram member 97. Initially ram 97 is positioned with its conductor plate 99 immediately adjacent working surface cover 83 of coil 71. The purpose of rivet 111 is to securely fasten together structural sheets 112 and 113 once it becomes formed by riveters 68, 69.

In operation rivet 111 is simultaneously deformed by receipt at its opposite ends of the simultaneous impact of rams '96 and 97 due to the simultaneous electric current flow through coils 70 and 71. This current ow is caused by the operators movement of control switch 67 from its full line position to its dashed line position, whereat capacitor 65 discharges through coils 70 and 71 simultaneously because of the series connection provided between the coils by means of series connector 79. The rapidly changing electrical current causes the repulsion of ram 96 in second direction 85 and ram 97 in first direction l84 such that rivet 111 receives a simultaneous impact at each of its ends through the contact with rivet dies 102 and 103 against it. The recoil of left riveter 68 is ab sorbed by recoil mass 86 as the friction between friction surface 88 and support surface 90 absorbs a certain amount of the recoil energy while resisting force 92 is applied in second direction to absorb the balance of the recoil energy. Similar recoil absorption occurs in righthand riveter l69 as friction surface 189 slides along support surface and resisiting force 93 is applied in first direction 84 directly opposite to the recoil direction of recoil mass `87. Once riveters 68 and 69 have reached equilibrium, resisting forces 92 and 93 are utilized to reposition coils 70 and 71 adjacent conductor plates 98 and 99 of respective rams 96 and 97. The repositioning of control switch `67 to its solid line position initiates the charging of capacitor 65 by means of power source 64 through charging leads `66. 'From this operation rivet 111 is properly deformed to securely fasten together structural sheets 113 and 112.

While the first two embodiments, 1 and `60, of high-impact tools have been shown in installations wherein the apparatus is mounted on a tool bench or other base support structure, the balance of this disclosure relates to a portable riveting system which can be taken to the workpieces being joined rather than requiring them to be brought to the bench. As shown in FIG. 3, portable riveting system 120 includes power supply 123 having a power source 124 connected to a variable capacitor 125 through charging leads 126 when the control switch 127 is in the full line position shown. The left-hand gun, which will be hereinafter referred to as main gun 130, is positioned opposite to right-hand or auxilitary gun 131.

Main gun 130 includes coil 132. The center terminal 134 of coil 132 is connected to the power supply 123 by means of discharging lead 136. The outer terminal 138 of main coil 132 is connected through series connector 140 to the outer terminal 139 of auxiliary coil 133 positioned within auxiliary gun 131. Center terminal of auxiliary coil 133 is connected by means of discharging lead 137 to power supply 123.

The main operator 142 is indicated in dotted lines as he applies first resisting force 148 to resist the recoil acting in the first direction, shown by arrow 144. In a similar manner auxiliary operator 143 applies a resisting force 149 to oppose the recoil of auxiliary gun 131 in the second direction, indicated by arrow 145. In normal usage the quantity of resisting forces 148 and 149, ranges between 20-35 pounds and is therefore easily within the capability of most operators including female operators. To avoid worker fatigue vertical supports 150 and 151 are used to hold up main and auxiliary guns 130 and 131. Through the utilization of counterbalance pulleys 152 and 153 suspended from overhead support 155 operators 142 and 143 can easily maneuver main and auxiliary guns 130 and 131 with the minimum of effort.

In the construction to be described in greater detail hereinafter, portable guns, such as main gun 130, have been constructed having as little weight as 35 pounds and with additional equipment more recent modelsl weigh less than 75 pounds. In a simplified form FIG. 3 illustrates the use of workpiece support 157 having a clamp 1518 for securely holdingworkpiece sheets 160 and 161 in a convenient position for the placement against the sheets of Working end 162 of main gun 130 and working end 163 of auxiliary gun 131. It is of course understood that different shapes, sizes, and locations of workpieces may require the operators to position their guns 130 and 131in something other than the horizontal plane shown in FIG. 3. For example, the plan in which both guns 130 and 131 lie might be vertical or inclined from either the vertical or horizontal plane as necessary to properly install the rivets into the workpieces.

For a more detailed description and appreciation of the features involved, reference is directed to FIG. 4 wherein a larger showing of main gun 130 illustrates its major internal as well as external structural components. For simplicity main gun 130 utilizes a cylindrical housing 165 which is closed at Athe rear end by closure plate 167. Attached to closure plate 167 is a pistol grip 1'68 which accommodates one hand of operator 142 for easy operation of trigger switch 169 mounted thereupon. To make the necessary electrical connection between the power supply 123 and main coil 132 a power cable connector structure 171 is slidably supported on gun housing 165 in a manner which permits power cables 172 attached to connector 171 to be rapidly cycled rearwardly as coil 132 recoils.

Additional guidance and operator control of main gun 130 is provided by side handle 174 which extends radially outwardly from gun housing 165 and includes in the body portion a series of control and indicator elements. These include auxiliary ready light 175, main alignment light 176, red charged light 178 mounted within the transluscent charge button 179, and green discharge light 1'81 mounted within green transluscent main stop button 182. It should be noted that charge button 179 and stop button 182 are conveniently positioned for actuation by the operators thumb as he steadies main gun 130 with the balance of his hand. While the working end 162 of main gun 130 will be described in greater detail with reference to FIGS. -7 it should be noted that it also includes an alignment uid conduit 184.

Mounted within housing 165, which is typically constructed of nylon or lightweight material coated with an insulating material, ram 1185 is positioned adjacent to and congured for guidance through working end 162. Conductor plate 1186 is attached to ram 185 such that it is positioned adjacent the working face cover 1:87 and coil assembly 188. In addition to the coil assembly 188, additional weight is provided by material extending rearwardly from coil assembly 188 to form recoil mass 189. The outer peripheral surfaces of coil assembly 188 and the balance of recoil mass 189 slides along the inner surface 191 of housing 165. Biased between rear end cover plate 167 and recoil mass 189 is positioned an absorptionrand restoration spring 192. To permit easy egress of air which might be otherwise trapped within the chamber formed within housing 165 between recoil mass 189 and rear end cover plate 167 there are provided rear end air vents 194 defined by and projected through end cover plate 1'67.

Although they are not shown, working end 162 of ,main

gun 130 may also include forward air vents to permit easy exit of the air displaced by ram 1185 as it is propelled away from main coil 132.

Because main and auxiliary guns 130 and 131 arev independently positionable by their respective operators 142 and 143, an alignment system 200 as shown in FIGS. 5-7 is provided to insure proper alignment so that the axis of the rivet being driven by the guns is coincident with the paths of the respective rams. As best shown in FIG. 5, forward end 162 of main gun 130 is positioned such that main die 202 secured to the end of ram stem 204 contacts on e endjof,rivet 201. The opposite end of rivet 201 is contactedby auxiliary die 203 which is secured to auxiliary ram Astem 205. The working surface 206 of main gun is positioned in contact with the exterior surface 210 of workpiece sheet and working surface 207 of auxiliary gun 13 17is positioned in contact with the exterior surface 2-11 of workpiece sheet 161.

Alignment channels 212 and 213 are formed in the working ends 162 and 163 of guns 130 and 131 to provide a pressure medium passage between main and auxiliary alignment outlets 214 and 215 and fluid or gas supply 220 through conduits 184 and 221. The fluid or gas under pressure from supply 220 is conducted through supply conduits- 184 and 221'as they pass through adjustable restrictors 222 and 223 and pressure sensitive switches 224 and 225. The restrictors cause a pressure drop in conduits 18,4 and, 221 when the fluid or gas flows. O-ring seals 216 and 217 are positioned, as shown in FIG. 7, in alignment outlets214 and 215such that as the working end 162 is positioned with working surfaces 206 in flush contact with working surface 210, O-ring seals 216 prevent the escape of the fluid or gas under pressure. This blocking of the outlets 214 stops the gas or uid ow through restrictor 222gand thus eliminates the normal pressure drop resulting in the supply pressure being sensed by pressure switch 224 causing it to close. When switch 224 is closed the electrical leads 228 and 230 carry the electric current from electrical potential 227, causing the lighting of main alignment light 176. This light remains lit as long as proper alignment is maintained with all of outlet 214 remaining blocked.

In a similar manner O-rings 217, positioned in outlets 215, will cause an increase in pressure in alignment channels 213 when auxiliary gun 131 is positioned with working surface 207 in flush contact with workpiece exterior sheet 211. Thisincrease in pressure causes the actuation of auxiliary pressure switch 225, which through the electrical circuit established from electric potential 227 and electric leads 229 and 231, causes auxiliary alignment light 177 to become lit.

' It'sh'ould be noted that any pressure medium could be used as an indicator of alignment. Good success has been obtainedby using a generally available plant low-pressure air supply. As will be described with reference to the electrical system shown in FIG. 8, working coils 132 and 133 of the main and'auxiliary guns 130 and 131 can not be `energized if either of the alignment pressure indicating switches 224 or y225 are open. Y

-JFIG. 6 illustrates the array of outlets 214 positioned in Working surface 206 of main gun 130. Although some `alignmentinformation could be obtained by the use of a single outlet,a more reliable and more accurate alignment is represented by the blocking of a plurality of out- `lets with three or four being preferred. Somewhat greater detail as to the design of specific outlet 214 is shown in FIG. 7 wherein it is noted that alignment channel 212 lopens into the outlet v214 which is surrounded by O-ring 'flush with exterior surface 210 of workpiece sheet 160.

Because th'e rivets currentlyin use in aircraft-industry requirestremendous forces to be adequately formed for..

fastening aircraft structures, it is necessary to provide very high voltages in the power'supply and to conduct very high currents from the power supply to working coils 132 and 133. -In a typical installation the charge on capacitor 125, mayvary between LOGO-10,000 volts, producing a current between 12,000 and 30,000 amps yielding 7,500- 118,000 joules as the charge on capacitor 125 is discharged thyroughthe coils 132 and 133 in from 20D-300 microseconds. p v

lIn view of the objects related above with regard to the interlocking operation between main and auxiliary guns 130 and 131, reference is now directed to FIG. 8 for a detailed description of the operating electrical system which provides the necessary means for obtaining the related objects. In essence the electrical system includes control circuit 287 shown in the upper portion of FIG. 8 which is interrelated With the power supply circuit 123 shown in the lower portion of FIG. 8. Control circuit 287 is basically a low voltage system wherein the input voltage is provided in circuit A by means of the electrical potential 227 establishing negative lead 289 and positive lead 290 when the system start switch 288 is closed. The condition of the electrical system shown in FIG. 8 is that in which power supply capacitor 125 is being charged. The sequence of operation therefore requires that initially the system start switch 288 is closed establishing the electrical potential between negative lead 289 and positive lead 290. Circuit B is activated when the power supply charged coil 292 pulls closed the power supply charged switch 293. This is indicated on the main gun by the lighting of the charged light 178 and on the auxiliary gun by lighting the auxiliary charge light 295. Circuit C becomes activated when the power supply has been discharged causing the power supply discharged coil 297 to pull closed the power supply discharge switch 298. This then is indicated on the main gun by the lighting of green light 181 and on the auxiliary gun by lighting the green light 299.

With reference as necessary to the discussion of the alignment system shown in FIGS. -7, it should be noted that circuit D of FIG. 8 is actuated first by the closing of auxiliary pressure switch 22S which indicates that the auxiliary gun is aligned by lighting the aligned light 177 on the auxiliary gun. The auxiliary operator 143, when he is ready, will actuate the ready trigger switch 301 which will be indicated on the main gun by lighting the auxiliary ready light 175 if auxiliary gun 131 is aligned closing switch 225. When the main gun is aligned, pressure switch 224 becomes closed lighting main gun aligned light 176 on the main gun and main gun aligned light 302 on the auxiliary gun. When all of these conditions of circuit D have been met and the main gun operator 142 is ready he will close ready trigger switch 169 Awhich will energize ready coil 304 sending a ready-to-tire signal 312 to the power supply 123.

As previously indicated the condition shown in FIG. 8 is that of charging of the power supply capacitor 125. Circuit E represents the means by which the depression of main gun charge button 179 will energize charge coil 308 to send a charge signal 326 to power supply 123 as long as the power supply charge switch 306 is not pulled open power supply charge coil 292 of circuit E. It should be noted that Circuit E is directly related to Circuit F in that the closure of either main stop button 18-2 or auxiliary stop switch 309 will open charge switch 179 of circuit E, and in addition will energize stop coil 310 sending a discharge signal 323 to power supply 123.

With continued reference to FIG. 8 and particularly the power portion thereof it is noted that power supply circuit 123 has been schematically illustrated as being interconnected by means of signals to the control system 287. Basically, however, the power supply 123 includes variable capacitor 125 which is shown as being charged by means of a closed connection provided by charging leads 126 from AC power source 321 through main line charge switch 327. Once capacitor 125 has reached the desired charge a power supply charged signal will be supplied to coil 292 and control circuits B and E as noted above.

In circuit E the actuation of power supply charged coil 292 opens power supply charge switch 306 which deenergizes charge coil 308 sending a reverse charge signal 326 which opens mainline charge switch 327 dicontinuing the charging of power supply capacitor 125. When all of the switches of circuit D have been closed the ready signal 312 will serve to close firing switch 127, opening grounding guillotine switch 3.14 and open discharge disconnect switch 320. While these operations have all been indicated as being performed by switches, they would most likely be performed by high voltage thyratron tubes useful in making and breaking circuits wherein high voltages are involved. In sequence, however, the opening of discharge disconnect switch 320 isolates AC power source 321 from any connection with power supply capacitor since the other side of AC power source 321 was opened by means of opening main line charge 327 which occurred upon reaching the desired charge of capacitor 125. The opening of grounding guillotine 314 isolates both sides of the output terminals 317 from ground and both sides of power supply 125 from ground. This is particularly important since the isolation of the charged power supply capacitor 125 from ground reduces the shock hazard to operators 142 and 143 since the potential on opposite sides of capacitor 125 is no longer related to ground and this condition exists during the short time in which the charge potential on power supply capacitor 125 is discharged through main coil 132 and auxiliary coil 133. The discharging of the power supply through coils 132 and 133 is simultaneous since the coils are connected in series by series connector 140.

Once power supply capacitor 125 has been discharged through working coils 132 and 133 the power supply charged coil 292 is no longer energized, permitting closure of power supply charge switch 306 in circuit E. If neither of the stop buttons 182 or 309 of circuit F have been closed then circuit E is completed causing the energizing of charge coil 308. This causes a charge signal 326 to pull closed main line charge switch 327. When either or both of the trigger switches 169 and 301 have been opened, the reverse ready signal 312 causes the restoration of the discharge disconnect switch 320 to its normal closed position permitting the charging of capacitor 125. At the same time grounding guillotine switch 314 reestablishes the reference to ground 315 for power supply capacitor 125 and tiring switch 127 resumed its normal open position.

We claim:

1. A high-energy impact apparatus comprising:

coil means adapted to be connected to an electric energy source for generating a rapidly changing energy iield adjacent to said coil;

ram means including a conductor plate and a workpiece-forming tool;

recoil means including said coil and a body member extending in a lirst direction from said coil;

frame means including a backstop member and guide means for guiding the movement of said ram means from a first position whereat said conductor plate is positioned adjacent said coil to a second position whereat said forming tool impacts a workpiece as said energy field changes propelling said ram away from said coil in a second direction opposite to said first direction;

absorption means positioned between said backstop member and said recoil mass for resisting movement of said recoil mass in said first direction and including restoration means for restoring said coil to said first position adjacent said ram conductor plate.

2. The apparatus of claim 1 wherein:

said absorption means includes a spring biased between said -backstop member and said recoil mass.

3. A riveting apparatus comprising:

a pair of riveting guns;

conductor means extending between each of said guns;

each of said guns including a rivet-forming ram, electromechanical means for receiving a rapidly changing electric current and converting it into mechanical energy for propelling said ram toward a rivet and operator control switch means for indicating that said gun is ready for receiving said current, one portion of said conductor means providing an electrical connection between said electrical connection between said electro-mechanic means of each of said guns for ensuring7 simultaneous operation of said guns once both of said operator ready indications are maintained.

4. The riveting apparatus of claim 3 including:

control means for operating said guns;

a second portion of said conductor means providingl a connection between each of said guns and said con-` trol means for transmitting said gun-originated indication of being ready to said control means;

said control means including iiring switch means connected between an electrical energy source and said electromechanical means, requiring the ready indication from both of said paired guns before permitting said rapidly changing electric current to pass through said electromechanical means of each of said guns.

5. The riveting apparatus of claim 3 including:

y power supply means and power cable means connected both of said ready indications andthe lack thereof,

permitting and preventing the communication between said guns and said power supply means.

6. The riviting apparatus of claim 3 including:

power supply means and power cable means connected between said power supply means and said guns for supplying said rapidly changing current thereto;

control means operatively connected among said guns and said power supply for selectively permitting and preventing the communication between said guns and said power supply means;

said control means including ready means responsive to receipt of said operator-ready indication;

said guns each including means for signalling the proper gun to workpiece alignment condition;

said control means including alignment means responsive to receipt of said gun alignment signal;

said control means being structured to permit said communication between said power supply and said guns whenever both of said guns are properly aligned and said operator control switches indicate as indicated by the condition of said ready and alignment means and to prevent said communication whenever any one of said desired alignment or ready conditions is not indicated by said ready and alignment means.

' 7. The riveting apparatus of claim 3 wherein:

each of said guns also includes an alignment-sensing means having means for sensing the relative attitude of the path of said ram and the surface of the workpiece adjacent the hole in which the rivet is positioned;

said alignment means including alignment switch means adapted to prevent said indication of said gun ready condition at least until a preselected attitude of said ram path and workpiece surface has been reached.

8. The riveting system of claim 7 wherein: V

said sensing means includes a plurality of pressure fluid channels provided in the ram end of said gun with outlets thereof formed in the surface ofsaid gun adapted for ilush contact with said workpiece f said outlets include a compressible seal member positioned therein toextend around said outlets for providing, when compressed against said workpiece, a

lfluid-tight seal. j 10. The riveting apparatus of claim 3 wherein:

one of said guns include means for sensing the proper alignment of said gun with said workpiece; said alignment sensing means includes means for signalling said proper alignment; second portion of said conductor providing means for communicating said alignment signal from one gun to the other of said guns; indicator means positioned on said other gun and connected with said second conductor portion for indicating on said other gun the alignment of said first gun.

'l -11., The riveting system of claim 10 wherein:

said conductor means includes a third portion for providing means for communicating the condition of said other gun;

' said other gun includes second indicator means connected with said third conductor portion for indicating on said other gun condition of said one gun operator control switch.

12. An impact tool apparatus comprising:

gun means including coil, ram and guide means;

said coil means providing means for generating a rapidly changing eld;

said ram means including a conductor plate and workl piece plate and workpiece-forming tool;

vsaid guide means providing ram guidance as it is prosaid floating ground means including connections with isolation switch positioned in said charging and discharging means and responsive to the firing position 5 ofsaid firing means for isolating said power supply v means from said charging and discharging means;

said tiring means providing a connection and disconnection` between said coil means and said power Vsupply means for supplying a rapidly changing current to said coil means, with said connection being `established when said firing means is in said firing position.

13. The apparatus of claim 12 wherein:

said gun means also includes alignment and operator `ready indicating means;

said ring means including connections with said gun alignment and ready indicating means for preventing positioning of said firing means in said iiring position until said indicating means indicates the desired alignment and readiness conditions for said gun.

14. The apparatus of claim 12 wherein:

said floating ground means operates to disconnect said power supply from said charging and discharging .means before the tiring connection between said 15. The apparatus of claim 12 wherein:

power supply and said coil is completed.

said gun means includes a discharge actuator for said discharging means permitting said operator to discharge said power supply into said ground.

16. The apparatus of claim 12 wherein:

said gun means includes a charge actuator for said charging means permitting said operator to cause said connection between said energy source and said power supply.

References Cited UNITED STATES PATENTS 1,232,050 7/1917 Kraemer 318-135X 14 2,920,783 1/1960 Kipp et al 29-243.53 3,453,463 7/1969 Wildi 173-117X FOREIGN PATENTS 1,122,153 1/1962 Germany.

JAMES M. MEISTER, Primary Examiner U.S. C1. X.R.

gyg UNITED STATES PATENT OFFICE CERTIFICATE 0F CORRECTION Patent No. 3 559 269 Dated Behr-Ham! 2 192] Inventor(s) H. A. Schmitt et al It is certified that: error appears in the above-identified patent and that said Letters Patent are hereby,r corrected as shown below:

Column ll, Line l should read --trical connection;

Column ll, Line +4 should read --and said operator v control switches indicate ready as in- Column l2, Line 5 should read --one of said guns includes means for sensing the proper;

Column l2, Line 30 should read --said ram means including a conductor plate and;

Column l2, Line 3l should read workpiece-forming tool;

column 12, Line 73 Should read --power Supply and said C011 is completed."

Column l2, Line 74 should read l5. The apparatus of claim l2 wherein:

Signed and sealed this 20th day of July 1971.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SGHUYLER, JR. Attesting Officer Commissioner of Patents 

